I imported some .arw(a raw file of sony) files into my photo library, and tried to open them in pixelmator. But I found it actually didn’t open the files as
raw files. Then I tried to open those files through iCloud. And it revealed as the photo below. Then I tapped “duplicates”, and it became the situation I open it through photo library.

Hey there, Pixelmator for iOS doesn't currently support editing RAW images natively, so that's why they're opened as uncompressed, regular images. But we're working on an app called Pixelmator Photo which is designed from the ground up for editing RAW photos, so that might be something to keep an eye on...